Wednesday, December 11, 2013

Earth and Moon from Juno fly-by

"Earth and Moon as seen from passing spacecraft"

D C AgleJet Propulsion Laboratory

Steve ColeNASA Headquarters

When NASA’s Juno spacecraft flew past Earth on October 9, 2013, it received a boost in speed of more than 7.3 kilometers per second, which set it on course for a July 4, 2016 rendezvous with Jupiter. One of Juno's sensors, a faint star tracking camera, also had a unique view of the Earth-Moon system. The result was an intriguing, if low-resolution, glimpse of what it would be like to approach our worlds from a distance.

“In the movie, you ride aboard Juno as it approaches Earth and then soars off into the blackness of space," said Scott Bolton, Juno principal investigator at the Southwest Research Institute (SwRI) in San Antonio. "No previous view of our world has ever captured the heavenly waltz of Earth and Moon."

The Juno Earth flyby movie is available on YouTube HERE. The original score is by Vangelis.

Ancient cosmic pirouette of Earth and Moon from the Jovian-bound spacecraft Juno as it flew by Earth, October 9, 2013 [NASA/JPL-Caltech].

The cameras that took the images for the movie are located near the pointed tip of one of the spacecraft's three solar-array arms. They are part of Juno's Magnetic Field Investigation (MAG) and are normally used to determine the orientation of the magnetic sensors. These cameras look away from the sunlit side of the solar array, so as the spacecraft approached, the system's four cameras pointed toward Earth. Earth and Moon came into view when Juno was about 966,000 kilometers away -- about thrice the Earth-Moon separation.

During the flyby, timing was everything. Juno was traveling about twice as fast as a typical satellite, and the spacecraft itself was spinning at 2 RPM.

To assemble a movie that wouldn't make viewers dizzy, the star tracker had to capture a frame each time the camera was facing Earth at precisely the right instant. The frames were then sent to Earth, where they were processed into video.

"Everything we humans are and everything we do is represented in that view," said the star tracker's designer, John Jørgensen of the Danish Technical University, near Copenhagen.

The Waves instrument aboard NASA's Juno spacecraft recorded amateur radio signals from ham radio operators from around the world [NASA/JPL-Caltech/University of Iowa].

Also during the flyby, Juno's Waves instrument, which is tasked with measuring radio and plasma waves in Jupiter's magnetosphere, recorded amateur radio signals. This was part of a public outreach effort involving ham radio operators from around the world. They were invited to say "HI" to Juno by coordinating radio transmissions that carried the same Morse-coded message. Operators from every continent, including Antarctica, participated.

"With the Earth flyby completed, Juno is now on course for arrival at Jupiter on July 4, 2016," said Rick Nybakken, Juno project manager at NASA's Jet Propulsion Laboratory in California

The Juno spacecraft was launched from Kennedy Space Center in Florida on August 5, 2011. Juno’s launch vehicle was capable of giving the spacecraft only enough energy to reach the asteroid belt, at which point the Sun’s gravity pulled it back toward the inner solar system. Mission planners designed the swing by Earth as a gravity assist to increase the spacecraft’s speed relative to the Sun, so it could reach Jupiter. (The spacecraft’s speed relative to Earth before and after the flyby was unchanged.)

Earth - over the coast of Namibia, from mosaic of images captured from the Juno spacecraft's on-board Junocam, near the Jupiter-bound probe's close encounter with Earth and Moon, October 9, 2013 [NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo].

After Juno arrives and enters into orbit around Jupiter the spacecraft will circle the planet 33 times, from pole to pole, and use its collection of science instruments to probe beneath the gas giant's obscuring cloud cover. Scientists will learn about Jupiter's origins, internal structure, atmosphere and magnetosphere.

Juno's name comes from Greek and Roman mythology. At times personified in Earth's Moon, Juno was the goddess of the civil state.

3 comments:

Ah so. Thanks, so much, Phil. I was under the false impression the spin configuration and other mission priorities had set aside the need for such a system. Nor do I remember where or when the issue came up.

Nice Info! This is done so that the solar Panels can absorb the maximum amount of sun power at any given time. The Solar Panels will vary in size and this depends on the requirement of the home or space.